I have built the Felicia Power supply, a pair of HT3 Speakers, and I have done some mods to my CD Player, Preamp, and P3a DAC. CD player went great, Preamp was fine, but I killed my P3a DAC. Be careful.
Start by building a kit of some sort to ket used to te idea of soldering and how to do these kinds of products. White Noise Audio, Mapletree, Bottlehead, and others have kits out there that you can cut your teeth on.
I recommend this because I just made a very expensive mistake trying to modify something that I was not ready for...